Many systems employ serial communications. In certain applications the serial link is designed for communication to be essentially only in one direction. However, at startup, or in the event of an error condition, it may be necessary to communicate some information back from the receiver to the transmitter. Also, if a card containing a serial receiver is hot-plugged into a system, the receiver needs to inform the transmitter of its existence. Conventionally, to implement this type of reverse communication requires a separate feedback path with an extra wire. If such a serial link with reverse communication is implemented for communication between integrated circuits, disadvantageously, additional pins are required on each of the communicating integrated circuits.